Tips and tricks

December 20 2022

General

• Keyboard shortcuts:

  Description	Mac	Windows
  Run lines of code	Command + Enter	Ctrl + Enter
  (Un)comment lines of code	Command + Shift + C	Ctrl + Shift + C
  Insert a foldable comments section	Command + Shift + R	Ctrl + Shift + R
  Reindent lines of code	Command + I	Ctrl + I
  Reformat lines of code	Command + Shift + A	Ctrl + Shift + A
  Attempt code completion	Tab	Tab
  Clear the console	Control + L	Ctrl + L
  Insert an assignment operator, <-	Alt + -	Alt + -
  Insert a pipe operator, %>%	Command + Shift + M	Ctrl + Shift + M
  Rename a variable in scope	Command + Shift + M + Alt	Ctrl + Shift + M + Alt

  Note: If you are running R 4.1+ you can switch to the native pipe operator, |>. To do this to to Preferences > Code and check the box “Use native pipe operator”.

  Note also: An easy way to remember the Rename in scope shortcut is Pipe + Alt.

• To encapsulate text in quotes or brackets, highlight the text, then type " or (.

• To generate code used to recreate an object:

  x <- data.frame(a = 2, b = 4)
  y <- dput(x)
  #> structure(list(a = 2, b = 4), class = "data.frame", row.names = c(NA, 
  #> -1L))
  y
  #>   a b
  #> 1 2 4

Writing loops

• To generate a sequence of numbers to iterate over:

  data <- c(1, 33, 100, 102)
  seq_along(data)
  #> [1] 1 2 3 4

  alternatively:

  data <- data.frame(a = 1:3, b = 4:6)
  seq_len(nrow(data))
  #> [1] 1 2 3

• To print a counter to the console:

  for (i in 1:3) {
    cat("\n", i)
  }
  #> 
  #>  1
  #>  2
  #>  3

  Note: \n moves the “print head” to a new line, whereas \r will move it back to the start of the same line.

Command history

• Keyboard shortcuts (from the console):

  Description	Mac	Windows
  Cycle through previous commands	Up arrow
  Show previous commands	Command + Up arrow
  Auto-complete commands (from previous)	Control + R

Writing functions

• To generate a function skeleton as a code snippet, type fun then hit tab and return (to select the snippet):

  name <- function(variables) {
  
  }

  Keep hitting tab to move from name to variables to the body of the function.

• Function extraction – to turn a chunk of code into a function, highlight a chunk of code, then press Control + Alt + X on Mac (or Windows) and enter a suitable function name when prompted. In doing so, this:

  x * y

  turns into this:

  multiply <- function(x, y) {
  x * y
  }

  Note: You can make your own custom code snippets in Tools > Global Options > Code and clicking Edit Snippets in the Snippets section.

Graphics

• To generate a sequence of evenly spaced values (useful when manually defining axis breaks in ggplot2):

  x <- c(0, 0.001, 1, 8)
  pretty(x)
  #> [1] 0 2 4 6 8

• To list the names of built in colours:

  x <- colors()
  head(x)
  #> [1] "white"         "aliceblue"     "antiquewhite"  "antiquewhite1"
  #> [5] "antiquewhite2" "antiquewhite3"

Packages

• Keyboard shortcuts:

  Description	Mac	Windows
  Document package	Command + Shift + D	Ctrl + Shift + D

Search

• To select the path of a file in your current directory, hit Tab inside of:

  ""

• To locate files relative to your project root, after installing the here package:

  library(here)
  #> here() starts at /home/runner/work/RPiR/RPiR
  here("R", "assert_no_globals.R")
  #> [1] "/home/runner/work/RPiR/RPiR/R/assert_no_globals.R"

• Keyboard shortcuts:

  Description	Mac	Windows
  Find files / functions	Control + .	Ctrl + .
  Search all files in a directory / project	Command + Shift + F

Miscellaneous

• Keyboard shortcuts:

  Description	Mac	Windows
  Show command palette	Command + Shift + P	Ctrl + Shift + P
  Keyboard shortcut reference	Alt + Shift + K
  Zoom in on an RStudio panel	Control + Shift + 1-4

• To find RMarkdown cheat sheets in RStudio, go to Help > Cheat Sheets > R Markdown Reference Guide. You can also find cheat sheets for dplyr, ggplot2, and devtools here.

• To automatically load packages on startup / restarting R:

  1. Create an .Rprofile file in your project root
  2. Fill it with anything you want loaded on startup

  Note that you should not use this to load in packages used in your analyses, such as dplyr or ggplot2.

  A useful example might be:

  library(devtools, quietly = TRUE)

  However, you can also populate it with any helper functions you might regularly use, or even R fortunes.

• To generate an R fortune, after installing fortunes:

  fortune()